Search Results

The target of substantial CO₂ reductions in the spirit of the Kyoto Protocol as well as higher engine efficiency requirements has increased research efforts into hybridization of passenger cars. In the frame of this hybridization, there is a real need to develop small Internal Combustion Engines (ICE) with high power density. The two-stroke cycle can be a solution to reach these goals, allowing reductions of engine displacement, size and weight while maintaining good NVH, power and consumption levels. Reducing the number of cylinders, could also help reduce engine cost. Taking advantage of a strong interaction between the design office, 0D system simulations and 3D CFD computations, a specific methodology was set up in order to define a first optimized version of a two-stroke uniflow diesel engine. The main geometrical specifications (displacement, architecture) were chosen at the beginning of the study based on a bibliographic pre-study and the power target in terms.

Fuel consumption in internal combustion engines and their associated CO2 emissions have become one of the major issues facing car manufacturers everyday for various reasons: the Kyoto protocol, the upcoming European regulation concerning CO2 emissions requiring emissions of less than 130g CO2/km before 2012, and customer demand. One of the most efficient solutions to reduce fuel consumption is to downsize the engine and increase its specific power and torque by using turbochargers. The engine and the turbocharger have to be chosen carefully and be finely tuned. It is essential to understand and characterise the turbocharger's behaviour precisely and on its whole operating range, especially at low engine speeds. The characteristics at low speed are not provided by manufacturers of turbochargers because compressor maps cannot be achieve on usual test bench.

Evolution of automotive diesel engines has led to the production of smaller and smaller engines with increasingly higher torque. The reduction in external dimensions means smaller flywheels, and the increase of torque rates, higher cyclic irregularities that today''s flywheels even with dual mass techniques are no longer able to cope with. Because of this, "damper" type absorber devices which control torque vibrations due to cyclic irregularities are no longer efficient to decrease rotating vibrations to an acceptable level. The best solution to cope with these problems is a tuned rotating pendulum: P.A.R.I.S. (Pendulum Acyclism Reducer Integrated System). This vibration absorber system can be easily integrated into a standard engine flywheel. P.A.R.I.S. systems show a very high efficiency level.